U.S. patent application number 15/240526 was filed with the patent office on 2017-02-23 for systems, methods, and devices for bipolar high voltage direct current electrical power distribution.
The applicant listed for this patent is GE Aviation Systems Limited. Invention is credited to Peter James HANDY.
Application Number | 20170054438 15/240526 |
Document ID | / |
Family ID | 54292005 |
Filed Date | 2017-02-23 |
United States Patent
Application |
20170054438 |
Kind Code |
A1 |
HANDY; Peter James |
February 23, 2017 |
SYSTEMS, METHODS, AND DEVICES FOR BIPOLAR HIGH VOLTAGE DIRECT
CURRENT ELECTRICAL POWER DISTRIBUTION
Abstract
Systems, methods and devices for aircraft power distribution
include a bipolar high voltage direct current source component; an
electrical loading component capable of drawing electrical power
from the bipolar high voltage direct current source component; a
set of switching components configured to selectively couple power
from the bipolar high voltage DC source component to the electrical
loading; and a transient suppression component. The transient
suppression component is configured to limit current flowing
through the first or the second subset of the set of switching
components when the first and the second subsets are not in the
same state.
Inventors: |
HANDY; Peter James;
(Cheltenmah, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GE Aviation Systems Limited |
Cheltenham |
|
GB |
|
|
Family ID: |
54292005 |
Appl. No.: |
15/240526 |
Filed: |
August 18, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02H 3/087 20130101;
H02J 3/36 20130101; H02H 3/05 20130101; H03K 17/0822 20130101; H02H
7/222 20130101; H02J 1/08 20130101; H02J 2310/44 20200101; H03K
17/18 20130101; H03K 2217/0054 20130101; B64D 2221/00 20130101 |
International
Class: |
H03K 17/082 20060101
H03K017/082; B64D 41/00 20060101 B64D041/00; H02J 3/36 20060101
H02J003/36; H03K 17/16 20060101 H03K017/16; H03K 17/18 20060101
H03K017/18 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 20, 2015 |
GB |
1514878.6 |
Claims
1. A system for aircraft power distribution, comprising: a bipolar
high voltage direct current source component with a positive
voltage lead and a negative voltage lead; an electrical loading
component capable of drawing electrical power from the bipolar high
voltage direct current source component; a set of switching
components configured to selectively couple power from the bipolar
high voltage direct current source component to the electrical
loading component by switching between an open state that decouples
power from the bipolar high voltage direct current source component
to the electrical loading component and a closed state that couples
power from the bipolar high voltage direct current source component
to the electrical loading component, wherein a first subset of the
switching components are coupled to the positive lead of the
bipolar high voltage direct current source component and a second
subset of the switching components are coupled to the negative lead
of the bipolar high voltage direct current source component; and a
transient suppression component coupled to the set of switching
components and configured to limit current flowing through the
first or the second subset of the set of switching components when
the first and the second subsets are not in the same state.
2. The system of claim 1, wherein the first subset of the switching
components includes a current limit level staggered from a current
limit level of the second subset of the switching components such
that when the electrical loading component experiences a short, the
first subset of the switching components is configured to limit
current before the second subset of the switching components.
3. The system of claim 1, wherein the bipolar high voltage direct
current source component includes two 270 volt direct current power
supplies.
4. The system of claim 3, wherein a negative lead of one of the two
270 volt direct current power supplies is coupled to a chassis
ground and the positive lead of the other of the two 270 volt
direct current power supplies is coupled to the chassis ground.
5. The system of claim 1, wherein the set of switching components
includes two solid-state power controllers.
6. The system of claim 1, further comprising a communications
component configured to apply an external voltage across a set of
control terminals of the set of switching components to a state of
the set of the switching components.
7. The system of claim 1, wherein the transient suppression
component includes a set of transient voltage suppressors or a set
of metal-oxide varistors.
8. The system of claim 7, wherein the transient suppression
component further includes a flywheel diode coupled across the
output of the set of switching components.
9. The system of claim 5, wherein the solid-state power controllers
include a monitoring module that determines if the switch current
in solid-state power controllers exceeds a predetermined threshold
and a control module that can set the state of both of the
solid-state power controllers in response to the determined switch
current.
10. The system of claim 5, wherein the solid-state power
controllers include a monitoring module that determines if the
temperature of the solid-state power controllers exceeds a
predetermined threshold and a control module that is configured to
set the state of both of the solid-state power controllers in
response to the determined temperature.
11. A method of distributing power, the method comprising: applying
power from a bipolar high voltage direct current source component
with a positive voltage lead and a negative voltage lead to an
electrical loading component capable of drawing power from the
bipolar high voltage direct current source component through a set
of switching components configured to selectively couple power from
the bipolar high voltage DC source component to the electrical
loading component by switching between an open state that decouples
power from the bipolar high voltage direct current source component
to the electrical loading component, and a closed state that
couples power from the bipolar high voltage direct current source
component to the electrical loading component, wherein a first
subset of the switching components are coupled to the positive lead
of the bipolar high voltage direct current source component and a
second subset of the switching components are coupled to the
negative lead of the bipolar high voltage direct current source
component; and limiting the current flowing through the set of
switching components when the first subset and the second subset
are not in the same state with a transient suppression
component.
12. The method of claim 11, further including the steps of
determining, by a monitoring module, if the switch current in the
set of switching components exceeds a predetermined threshold, and
setting, by a control module, the state of the set of switching
components in response to the determined switch current.
13. The method of claim 11, further including the steps of
determining, by a monitoring module, if the temperature in the set
of switching components exceeds a predetermined threshold, and
setting, by a control module, the state of the set of switching
components in response to the determined temperature.
14. The method of claim 11, further including a step of staggering
a current limit level of the first subset of the set of switching
components from a current limit level of the second subset of the
switching components such that when the electrical loading
component experiences a short, the first subset of the switching
components limits current before the second subset of the switching
components.
15. A power switching device, comprising: a set of switching
components configured to selectively couple power from a bipolar
high voltage direct current source component to an electrical
loading component by switching between an open state that decouples
power from the bipolar high voltage direct current source component
to the electrical loading component and a closed state that couples
power from the bipolar high voltage direct current source component
to the electrical loading component wherein a first subset of the
switching components are coupled to the positive lead of the
bipolar high voltage direct current source component and a second
subset of the switching components are coupled to the negative lead
of the bipolar high voltage direct current source component; and a
transient suppression component coupled to the set of switching
components and configured to limit current flowing through the
first or the second subset of the set of switching components when
the first and the second subsets are not in the same state.
16. The power switching device of claim 15, wherein the set of
switching components are configured to selectively couple power
from the bipolar high voltage direct current source component that
includes two 270 volt direct current power supplies.
17. The power switching device of claim 16, wherein a negative lead
of one of the two 270 volt direct current power supplies is coupled
to a chassis ground and the positive lead of the other of the two
270 volt direct current power supplies is coupled to the chassis
ground.
18. The power switching device of claim 15, wherein the set of
switching components includes two solid-state power
controllers.
19. The power switching device of claim 15, wherein the transient
suppression component includes a set of transient voltage
suppressors or a set of metal-oxide varistors.
20. The power switching device of claim 19, wherein the transient
suppression component further includes a flywheel diode coupled
across the output of the set of switching components.
Description
BACKGROUND
[0001] Electrical power distribution systems manage the allocation
of power from energy sources to electrical loads that consume
distributed electrical power. In aircraft, gas turbine engines for
propulsion of the aircraft typically provide mechanical energy that
ultimately powers a number of different accessories such as
generators, starter/generators, permanent magnet generators (PMG),
fuel pumps, and hydraulic pumps, e.g., equipment for functions
needed on an aircraft other than propulsion. For example,
contemporary aircraft need electrical power for electrical loads
related to avionics, motors, and other electric equipment.
[0002] Over time, aircraft electrical power source voltages have
increased. Aircraft with 14- and 28-volt direct current (VDC)
electrical power systems have given way to aircraft with electrical
power systems operating at 115 volts alternating current (VAC) and
230 VAC. Presently, aircraft can include one or more electrical
power sources that operate at voltages including plus/minus 270
VDC. For example, a current wide-body twin-engine commercial
jetliner uses an electrical system that is a hybrid voltage system
that includes sub-systems operating at voltages of 230 VAC, 115
VAC, 28 VDC along with a bipolar, high voltage, direct current
subsystem that includes plus and minus 270 VDC sources.
[0003] The voltages in the high-voltage DC electrical systems reach
levels comparable to domestic AC systems and need to include fault
mitigation features to detect and react to abnormal electrical
current flow that can occur in the system. In domestic AC systems
fault protection devices typically include a circuit breaker that
can trip to an off position, typically by way of an
electromechanical switch that can actuate in approximately 50
milliseconds (ms) to de-energize the feed line in the event of a
fault condition. An electromechanical switch passing current from a
high-voltage DC source to an electrical load draws an arc on
opening the switch when the electron flow across the opening switch
contacts ionizes the air molecules across the gap between the
contacts to form a gas plasma. The plasma is of low resistance and
is able to sustain power flow. The plasma is hot and capable of
eroding the metal surfaces of the switch contacts. Electric current
arcing causes degradation of the contacts and therefore the
electromechanical switch and also electromagnetic interference
(EMI) that can require the use of arc suppression methods.
BRIEF DESCRIPTION
[0004] In one aspect, a system for aircraft power distribution
includes a bipolar high voltage direct current source component
with a positive voltage lead and a negative voltage lead; an
electrical loading component capable of drawing electrical power
from the bipolar high voltage direct current source component; a
set of switching components configured to selectively couple power
from the bipolar high voltage DC source component to the electrical
loading component by switching between an open state that decouples
power from the bipolar high voltage direct current source component
to the electrical loading component and a closed state that couples
power from the bipolar high voltage direct current source component
to the electrical loading component wherein a first subset of
switching components are coupled to the positive lead of the
bipolar high voltage direct current source component and a second
subset of switching components are coupled to the negative lead of
the bipolar high voltage direct current source component; and a
transient suppression component. The transient suppression
component is configured to limit current flowing through the first
or the second subset of the set of switching components when the
first and the second subsets are not in the same state.
[0005] In another aspect, a method of distributing power includes
applying power from a bipolar high voltage direct current source
component with a positive voltage lead and a negative voltage lead
to an electrical loading component capable of drawing power from
the bipolar high voltage direct current source component through a
set of switching components configured to selectively couple power
from the bipolar high voltage DC source component to the electrical
loading component by switching between an open state that decouples
power from the bipolar high voltage direct current source component
to the electrical loading component and a closed state that couples
power from the bipolar high voltage direct current source component
to the electrical loading component wherein a first subset of
switching components are coupled to the positive lead of the
bipolar high voltage direct current source component and a second
subset of switching components are coupled to the negative lead of
the bipolar high voltage direct current source component and
limiting the current flowing through the set of switching
components when the first subset and the second subset are not in
the same state with a transient suppression component.
[0006] In another aspect, a power switching device, includes a set
of switching components configured to selectively couple power from
a bipolar high voltage DC source component to an electrical loading
component by switching between an open state that decouples power
from the bipolar high voltage direct current source component to
the electrical loading component and a closed state that couples
power from the bipolar high voltage direct current source component
to the electrical loading component wherein a first subset of
switching components are coupled to the positive lead of the
bipolar high voltage direct current source component and a second
subset of switching components are coupled to the negative lead of
the bipolar high voltage direct current source component and a
transient suppression component coupled to the set of switching
components. The transient suppression component is configured to
limit current flowing through the first or the second subset of the
set of switching components when the first and the second subsets
are not in the same state.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] In the drawings:
[0008] FIG. 1 is an example top down schematic illustration of an
aircraft and electrical power distribution system in accordance
with various aspects described herein.
[0009] FIG. 2 is an example diagram of a high voltage DC electrical
power distribution system in accordance with various aspects
described herein.
[0010] FIG. 3 is a flowchart illustrating a method of distributing
power on a bipolar high voltage DC electrical power system in
accordance with various aspects described herein.
[0011] FIG. 4 is an example schematic illustration of a bipolar
high voltage electrical power distribution system in accordance
with various aspects described herein.
[0012] FIG. 5 is an example schematic illustration of a bipolar
high voltage electrical power distribution system in accordance
with various aspects described herein.
[0013] FIG. 6 is an example schematic illustration of a bipolar
high voltage electrical power distribution system in accordance
with various aspects described herein.
[0014] FIG. 7 is an example plot of voltage and current waveforms
that demonstrates the operation of the bipolar high voltage
electrical power distribution system in accordance with various
aspects described herein.
[0015] FIG. 8 is an example plot of voltage and current waveforms
that demonstrates the operation of the bipolar high voltage
electrical power distribution system in accordance with various
aspects described herein.
DETAILED DESCRIPTION
[0016] The embodiments of the present disclosure are described
herein in the context of an aircraft, which enables production of
electrical power from an energy source such as a turbine engine,
jet fuel, hydrogen, etc. However, it will be understood that while
one embodiment is shown in an aircraft environment, the scope is
not so limited and embodiments have general application to
electrical power distribution systems in non-aircraft applications,
such as other mobile applications and non-mobile industrial,
commercial, and residential applications. For example, applicable
mobile environments can include an aircraft, spacecraft,
space-launch vehicle, satellite, locomotive, automobile, etc.
Commercial environments can include manufacturing facilities or
power generation and distribution facilities or infrastructure.
[0017] At least some of the embodiments provide for bipolar
high-voltage electrical power distribution systems, methods and
apparatuses that include transient detection and mitigation
capabilities. The bipolar high-voltage electrical power
distribution system includes a set of switching components such as
solid-state power controllers (SSPC). It will be understood that "a
set" can include any number of solid-state switches, including a
single solid-state switch. Similarly, "a set" as used herein can
include any number of elements, including a single element. It will
be understood that a bipolar DC power supply or bipolar DC power
source as used herein can be defined as a source of direct current
electrical power where the output voltage can be set to positive or
negative and can source current. It will be understood that high
voltage DC as used herein can be defined as electrical energy at
voltages high enough to damage solid-state components in the event
of an electrical fault and can include but is not limited to
voltages greater than provided by 28 VDC electric power sources
integrated into many conventional aircraft.
[0018] Currently, few aircraft include bipolar high-voltage power
sources such as plus and minus 270 VDC and none of these aircraft
integrate an electrical power distribution system for bipolar
high-voltage power. However, with the provision of a high-voltage
DC electrical distribution system, bipolar high-voltage DC sources
will no longer be confined to a single area of the aircraft.
Consequently, bipolar high-voltage DC sources, by way of the
electrical distribution system, will need the capability to
suppress transient electrical activity and mitigate fault events
that can occur anywhere on the aircraft where a load is powered by
the bipolar high-voltage DC source.
[0019] Because of issues associated with electromechanical switches
related to reliability and switching speed, solid-state switches
are typically used in safety-critical power systems, such as those
found in aircraft and including high voltage DC power applications.
Solid-state switches are susceptible to damage resulting from a
transient response in a circuit or electrical system. Electrical
power systems such as provided on aircraft are exposed to a number
of potential sources for transient electrical activity including,
but not limited to equipment failure and lightning strikes. A
transient protection scheme for high-voltage DC electrical
distribution systems includes coordinating the timing of opening
and closing the solid-state switches coupled to the positive and
negative feeds a high-voltage DC source. The coordination of the
solid-state switches includes a protective measure such that if a
solid-state switch coupled to one of the positive and negative
feeds fails, the other is not damaged.
[0020] Turning now to FIG. 1, an example top down schematic
illustration of an aircraft and electrical power distribution
system in accordance with various aspects described herein is
shown. An aircraft 2 illustrated as having at least one gas turbine
engine, shown here as a left engine system 12 and a right engine
system 14 which can be substantially identical to each other. The
aircraft 2 can have any number of engine systems. The left engine
system 12 can be coupled to one or more electrical power sources 16
that convert mechanical energy into electrical power. It will be
understood that any or all of the engines in an aircraft 2,
including the left and right engine systems 12, 14 can be so
coupled to one or more bipolar high-voltage DC electrical power
sources 16. The bipolar high-voltage DC power source 16 can be
coupled to an electrical power distribution system 18 that
selectively energizes a set of systems and devices on the aircraft
2 that collectively make up the electrical load. Systems and
devices powered by the bipolar high-voltage DC power source 16 by
way of the electrical power distribution system 18 can be any
system or device on an aircraft capable of drawing an electrical
load and include, but are not limited to, flight control actuators
26, localized down-convertors 27 for cockpit displays,
environmental control systems 28, etc.
[0021] In the aircraft 2, the operating left and right engine
systems 12, 14 provide mechanical energy that can be extracted via
a spool, to provide driving force for the bipolar high-voltage DC
power source 16. Other power sources can include but are not
limited to generators, batteries, fuel cells, backup power sources
such as a Ram Air Turbine (RAT), rectifiers for converting one or
more AC source inputs to a bipolar high-voltage DC source etc. The
electrical power source 16, in turn, provides the generated power
to the electrical loads for the systems and devices 26, 27, 28 for
load operations which is distributed by the electrical power
distribution system 18.
[0022] Turning now to FIG. 2, an example diagram of a bipolar
high-voltage DC electrical power distribution system 50 in
accordance with various aspects described herein is shown. The
bipolar high-voltage DC electrical power distribution system
includes a bipolar high voltage DC source component 52 coupled to a
set of switching components 54. The set of switching components 54
selectively couples power from the bipolar high voltage DC source
component 52 to an electrical loading component 58. The set of
switching components 54 includes a transient suppression component
56 to limit current flowing through the set of solid-state
switching components during a transient voltage event. A
communications component 60 is coupled to the set of switching
components 54 to control and monitor the state of the set of
switching components 54.
[0023] The bipolar high voltage DC source component 52 is a bipolar
high-voltage DC power source or supply. The bipolar high voltage DC
source component 52 can output any positive and negative voltage
level for use in distributing electrical power to an electrical
loading component 58 including but not limited to positive and
negative 270 V.
[0024] The set of switching components 54 includes a set of
solid-state switches. The set of solid-state switches can include
any type of solid-state switch capable of switching on or off (i.e.
closed or open) when an external voltage is applied across a set of
control terminals of the switch. Each of the solid-state switches
in the set of switching components 54 can include a solid-state
electronic switching device which switches power to the load
circuitry of the electrical loading component 58, and a coupling
mechanism to enable the control signal to activate the switch
without electromechanical components. The set of switching
components 54 can be any type of solid-state electronic switches
including but not limited to a solid-state power controller (SSPC),
a solid-state relay including a single metal-oxide-semiconductor
field-effect transistor (MOSFET), a solid-state relay including
multiple MOSFETs arranged in a parallel configuration, etc. The
semiconductor switching elements of the set of switching components
can be formed of any material used for solid-state switching
electronic applications including but not limited to silicon,
silicon carbide, gallium nitride, etc.
[0025] One configuration of the set of switching components 54
includes the provision of SSPCs which are semiconductor devices
that control electrical power supplied to a load. Additionally,
SSPCs perform supervisory and diagnostic functions in order to
identify overload conditions and prevent short circuits.
Functionally, SSPCs are similar to circuit breakers with
electromechanical switching elements that will protect wiring and
loads from faults. SSPCs can switch states within the order of
microseconds in comparison to electromechanical switches that can
require approximately 30 ms or more to complete a transition from
one state to another. Implemented with SSPCs, the set of switching
components 54 can include built-in monitoring and protection
features including but not limited to voltage monitoring, current
monitoring, temperature monitoring to ensure that the negative and
positive SSPCs do not overheat, current limiting, I.sup.2t
monitoring, arc fault protection, and low-fidelity ground fault
protection, etc. The built-in monitoring and protection features of
SSPCs enable the set of switching components 54 to function as a
controller that can control outputs to loads to ensure proper
operations. SSPCs can include configurable microprocessors that can
be programmed to increase controlling characteristics. Each SSPC
can include any configuration, topology or electronic components
for use in switching power in the high voltage DC electrical power
distribution system 50 including but not limited to the provision
of each SSPC to include one or more semiconductor devices in
parallel to boost current carrying capability, the configuration of
SSPCs to be bidirectional by using two unidirectional devices in
series, etc.
[0026] The set of switching components 54 can include any number of
switches including but not limited to one switch coupled to a
positive lead from the bipolar high voltage DC source component 52
and a second switch coupled to a negative lead from the bipolar
high voltage DC source component 52. Therefore, in one
configuration, the set of switching components 54 includes a first
SSPC coupled to a positive lead from the bipolar high voltage DC
source component 52 and a second SSPC coupled to a negative lead
from the bipolar high voltage DC source component 52.
[0027] The communications component 60 controls and monitors the
state of the set of switching components 54 in part by
communicating with other control elements of the aircraft. For
example, the communications component 60 reports the status of the
SSPCs back to other vehicle management control systems. The
communications component 60 can transmit data indicative of
commands to the switch, read a status of the switch that includes
whether the switch is open or closed, and monitor a health of the
switch. For instance the status of the switch can include an
indication of whether the switch is open or closed, and the health
of the switch can include a temperature indication. The
communications component 60 can be based on any data communications
hardware and protocol capable of transmitting data related to the
control and the state of the set of switching components 54
including but not limited to a balanced interconnecting cable
configured to implement Recognized Standard 485 (RS-485), a two
wire serial cable configured to implement controller area network
(CAN bus) protocol, a three or five wire serial cable configured to
implement Recognized Standard 232 (RS-232), etc.
[0028] The transient suppression component 56 limits the flow of
current through the set of switching components 54 in the bipolar
high voltage DC distribution system 50. With a bipolar high voltage
electrical distribution system 50, current travels from the bipolar
high voltage DC source component 52, out to the set of switching
components 54, out to the electrical loading component 58 and then
back again. Therefore, the transient suppression component 56 is
configured to limit or arrest current flowing through the set of
switching components 54 during an over-voltage condition that can
potentially sink a damaging level of current in one or more of the
set of switching components 54. The transient suppression component
56 can be formed from and configured with any device capable of
limiting current through a solid-state switching element including
but not limited to a metal-oxide varistor (MOV), a transient
voltage suppressor (TVS), flywheel (i.e., flyback, suppression,
clamp, etc.) diode and combinations thereof that include elements
internal and external to the set of switching components 54.
[0029] Referring now to FIG. 3, a flowchart illustrating a method
100 of distributing power on a bipolar high voltage DC electrical
power system 50 in accordance with various aspects described herein
is shown. At 110, the bipolar high voltage DC source component 52
applies power to the bipolar high voltage DC distribution system
50. Depending on the type or configuration of the bipolar high
voltage DC source component 52, the application of power can
include activating a generator, starting an engine, issuing a
control command to energize the source, closing one or more
circuits, etc. During normal or idealized operations, the set of
switching components 54 close and the electrical loading components
58 are energized and correctly sink power as per the operational
requirements of the electrical loading components 58. In abnormal
operations or even in actual, nominal real-world operations, the
set of switching components 54 are not always in the same state.
For example, one switch can be open when another is closed. In some
instances, the asymmetry in the state of the set of switching
components 54 occurs because of a fault in the bipolar high voltage
DC power distribution system 50. In other instances, the asymmetry
in the state of the set of the switching components 54 occurs
because of a lack in simultaneity of the switching events. That is,
one switch changes state before another switch in the set of
switching components 54. The lack of simultaneity in the switching
of the set of switching components 54 occurs, in part, because of
the finite level of coordination that can be achieved with
electronic control. Additionally or alternatively, the lack of
simultaneity can be further exacerbated by operational requirements
that can include, but are not limited to, physical separation of
the switches. For instance, switches are often separated by at
least one foot to enforce electrical isolation due to the high
voltage of the bipolar high voltage DC electrical power system 50.
The physical separation can cause minor unsynchronized switching to
occur due to delays in communication between switches.
[0030] Therefore, at step 112, a determination of the state of the
set of switching components 54 includes determining whether all of
the switches are open or closed. If all of the switches in the set
of switching components 54 are not in the same state, the transient
suppression component 56 limits the current flowing through the set
of solid-state switching components 54. At step 114, the transient
suppression component 56 limits the current flowing through the set
solid-state switching components 54 to provide a protective measure
for the set of solid-state switching components 54.
[0031] Referring now to FIG. 4, an example schematic illustration
of a bipolar high voltage electrical power distribution system 200
in accordance with various aspects described herein is shown. The
bipolar high voltage DC source component 210 includes two high
voltage DC sources 211 each coupled to chassis ground 236, one by
the negative lead and the other by the positive lead. The bipolar
high voltage DC source component 210 is coupled to the set of
switching components 216 which includes two SSPCs 212 and 214; a
first SSPC 212 coupled to the positive side of the bipolar high
voltage DC source component 210 and a second SSPC 214 coupled to
the negative side of the bipolar high voltage DC source component
210. The coupling between the bipolar high voltage DC source
component 210 and the set of switching components 216 can include
current limiting wire 238. The set of switching components 216 are
coupled to the electrical loading component 226. The coupling
between the set of switching components 216 and the electrical
loading component 226 can include current limiting wire 238.
[0032] The first and second SSPC 212, 214 can include a number of
subcomponents and modules for controlling and protecting the set of
switching components 216. An SSPC 212, 214 can include a main solid
state switch 224 that opens or closes to couple or decouple the
electrical loading component 226 to the bipolar high voltage DC
source component 210. As shown in FIG. 4, the main solid state
switch 224 can include the transient suppression component 225
which can be formed of one or more protective elements including
but not limited to a metal-oxide varistor (MOV), a transient
voltage suppressor (TVS), etc. The transient suppression component
225 reacts to sudden or momentary overvoltage conditions indicative
of a transient event and limits current flow through the main
switch 224. An SSPC 212, 214 can include one or more snubber
circuits 228 across the input of the switch, the output of the
switch or both, to suppress voltage spikes and dampen ringing
caused by circuit inductance when a switch opens. An SSPC 212, 214
can include one or more built-in test circuits 230 to provide
Built-In Testing (BIT) features. The built-in test circuit 230
allows for operation of an Initiated Built-In Test (MIT) scheme
that enables self-testing of the SSPC 212, 214 to verify proper
functioning of the SSPC 212, 214. The built-in test circuit 230 can
test any feature of the SSPC and includes but is not limited to an
arc fault detection circuit for the detection of an arc fault. When
both SSPCs are open the voltage developed at the output of each
SSPC due to semiconductor leakage is managed by resistive element
240, 241 coupled to the output of the SSPC 212, 214 and chassis
ground 236. The SSPC 212, 214 can include a switch control
subcomponent 222 that can coordinate communications with external
communication components 234, enable protective functions via a
monitoring module 218 and control the state of the main switch 224
of the SSPC 212, 214. The monitoring module 218 can include any
monitoring features for determining potential events that can
damage the switch including but not limited to voltage monitoring,
current monitoring, temperature monitoring, current limiting,
I.sup.2t monitoring, arc fault protection, and low fidelity ground
fault protection, etc. The SSPC 212, 214 can provide differential
feed fault protection where the output current of the positive SSPC
212 and the negative SSPC 214 is compared in order to determine a
gross ground fault. The monitoring module 218 can monitor the
output current and voltage at the SSPCs 212, 214 to provide series
and parallel arc fault detection. The SSPCs 212, 214 include closed
loop current limiting where each SSPC 212, 214 uses local
closed-loop current feedback to ensure that current is shared
evenly between SSPCs 212, 214 during current limiting events. The
monitoring module 218 can provide current limiting by any
configuration or technique useful for current limiting solid-state
devices including but not limited to linear current limiting and
pulse-width modulation (PWM) techniques. The control module 220 can
control the state of the main switch 224 based on inputs from
either external communications components 234 or the monitoring
module 218 or combinations thereof.
[0033] By implementing the above-defined monitoring and protective
measures the bipolar high voltage electrical power distribution
system 200 can implement a number of steps to control and
coordinate the SSPCs 212, 214. For example, the bipolar high
voltage electrical power distribution system 200 includes the
capacity to continuously monitor the status of each main switch 224
when they are in the open and closed states. When each main switch
224 is in a closed state, the monitoring module 218 can implement
the I.sup.2t wire protection where if the monitoring module 218
determines that current deviated from a predetermined threshold
curve, a command from the control module can set both main switches
224 to the open state. The predetermined threshold can be any
current versus time curve that determines the I.sup.2t trip
including but not limited to aerospace and industry standards that
provide sample curves. Similarly, if the monitoring module 218
determines that the switch current in either SSPC 212, 214 exceeds
a predetermined threshold, the current can be limited and main
switches 224 tripped to the open state. The predetermined threshold
can be any current level depending on the number of switching
semiconductors available to pass current through the SSPC including
but not limited to a current levels ranging between 10 and 1000
amperes (A). If the monitoring module determines that the
temperature for an SSPC 212, 214 exceeds a nominal level, the
control module 220 can set both SSPCs 212, 214 to the open state or
report back to an external control component via the communications
component 234. The nominal level can be any temperature depending
on the particular SSPC including but not limited to 100 degrees
Celsius (.degree. C.).
[0034] When using two current limiting SSPCs 212, 214 in series, as
shown in FIG. 4, if the current limit levels for each SSPC 212, 214
are equal, the bipolar high voltage electrical power distribution
system 200 can experience instability in the closed loop current
control. Consequently, the set of switching components 216 can
include staggered current limit levels for each SSPC 212, 214. For
example, the positive SSPC 212 current limit can be set to 600% and
the negative SSPC current limit 214 can be set to 500%. In this
way, the staggered current limit levels ensure that during a
shorted load scenario that the positive SSPC 212 limits current
first. Voltages and currents are monitored for status and health
monitoring purposes. The SSPC 212, 214 can include elements and
methods for controlling semiconductor leakage including but not
limited to a bleed resistor 240. When switching the state of an
SSPC 212, 214, so-called "turn on" and "turn off" events, the SSPC
212, 214 can control the load voltage dV/dt within a specific band
by providing closed loop feedback on dV/dt. The specific band can
be any voltage change per unit time, including but not limited to
100 V/microsecond for each switch in a plus and minus 270 VDC
system. During SSPC "turn on" and "turn off" events, the SSPC 212,
214 can ramp the current limit set point to control the rate of
rise of load current &Mt.
[0035] FIG. 5 is an example schematic illustration of a bipolar
high voltage electrical power distribution system 300 in accordance
with various aspects described herein. The bipolar high voltage
electrical power distribution system is similar to that illustrated
in FIG. 4; therefore, like parts will be identified with like
numerals increased by 100, with it being understood that the
description of the like parts of the first bipolar high voltage
electrical power distribution system applies to the second bipolar
high voltage electrical power distribution system, unless otherwise
noted. FIG. 5 includes a transient suppression component 325 with
an additional element shown as a flywheel diode 350 external to the
set of switching components 316. The flywheel diode 350 can reduce
the transient energy dissipated in the MOV or TVS devices across
the main switch 324 of the SSPCs 312, 314. FIG. 6 is an example
schematic illustration of a bipolar high voltage electrical power
distribution system 400 in accordance with various aspects
described herein. The transient suppression component 425 includes
the flywheel diode 450 across the outputs of the set of switching
components 416. The MOV or TVS devices 452, 454 are located across
the inputs of the SSPCs 412, 414. Whereas in FIG. 5 and FIG. 6, the
two SSPCs 212, 214, 312, 314 need to be co-located to reduce losses
in the wiring of the flywheel diode 350,450, with the configuration
in FIG. 4, the set of switching components 216 do not need to be
co-located.
[0036] FIG. 7 is an example plot of voltage and current waveforms
that demonstrates the operation of the bipolar high voltage
electrical power distribution system in accordance with various
aspects described herein. The plot demonstrates how the
above-described switch topology handles unsynchronized switching of
the positive SSPC 212, 312, 412 and negative SSPC 214, 314, 414
such as occurs when the positive SSPC 212, 312, 412 and negative
SSPC 214, 314, 414 are not co-located. At time (1), power is
applied to the bipolar high voltage DC source component 52 which is
a positive and negative 270 VDC supply such as shown in FIG. 4-6 as
210, 310, 410. The current through the set of SSPCs 216, 316, 416
increases momentarily as the capacitors of the input and output
snubbers 228, 328, 428 charge. The voltage on each SSPC in the set
of SSPCs 216, 316, 416 input rises to plus and minus 270 VDC and
with the main switches 224, 324, 424 of the set of SSPCs 216, 316,
416 set to an open state, the voltage across both the positive and
negative main switches 224, 324, 424 is 270 VDC.
[0037] At time (2), the main switch 224, 324, 424 of the negative
SSPC 214, 314, 414 closes and the voltage across the main switch
224, 324, 424 of the negative SSPC 214, 314, 414 reduces to 0 V and
the output voltage ("V.sub.OUT Negative") from the negative SSPC
214, 314, 414 reduces to -270 V. Similarly, because the potential
is present at the electrical loading component 226, 326, 426, the
output voltage ("V.sub.OUT Positive") of the positive SSPC 212,
312, 412 also reduces to -270 V. The voltage across the main switch
of the positive SSPC 212, 312, 412 is 540 VDC. During this time,
the load voltage remains at zero because the main switch 224, 324,
424 of the positive SSPC 212, 312, 412 has not been set to a closed
state. The total current ("I.sub.Total Positive" and "I.sub.Total
Negative") is small because of the charging of the positive and
negative output snubbers 228, 328, 428.
[0038] At time (3), the main switch 224, 324, 424 of the positive
SSPC 212, 312, 412 is set to the closed state and the voltage
across the main switch 224, 324, 424 of the positive SSPC 212, 312,
412 reduces to 0 V and the output voltage of the positive SSPC 212,
312, 412 rises to positive 270 V. Similarly, the electrical loading
component 226, 326, 426 is electrically coupled to the bipolar high
voltage DC source component 210, 310, 410 and, therefore, the load
voltage increases to 540 V and the total current rises to the 100%
rated current (e.g. 120 A).
[0039] At time (4), the main switch 224, 324, 424 of the positive
SSPC 212, 312, 412 is set to the open state and the voltage across
the main switch 224, 324, 424 of the positive SSPC 212, 312, 412
increases to approximately 1 kV due to the MOV/TVS-clamped back
electromotive force (EMF) caused by wiring loop inductance. The
voltage across the main switch 224, 324, 424 of the positive SSPC
212, 312, 412 reduces to a steady state of 540 V. The load voltage
also reduces to zero and the total SSPC output currents reduce to 0
A.
[0040] The plots in FIG. 8 show when the main switch 224, 324, 424
of the negative SSPC 214, 314, 414 is set to the open state at time
(5). Because the output snubbers 228, 328, 428, each hold
significant energy and the leakage resistors 240, 241, 340, 341,
440, 441 include relatively high resistance values to reduce steady
state losses, the capacitors of the snubbers 228, 328, 428
discharge in approximately 25 ms. Therefore the positive and
negative output voltages and the positive and negative main switch
voltages do not return to 0V, 0V, 270V and 270V respectively until
25 ms after the main switch 224, 324, 424 of the negative SSPC 214,
314, 414 is set to the open state.
[0041] Potentially beneficial effects of a high voltage DC bipolar
power distribution in aircraft is that high levels of power can be
delivered to a given load at lower current levels compared with
those required in low voltage DC systems. In some cases the
required current for a given load reduces given a constant power
requirement and this therefore reduces the required wire gauge for
a given load thus resulting in lighter wiring. Potentially
beneficial effects of the above-described embodiments for solid
state switching of high voltage DC bipolar power supplies include
fast protection of and current limiting during short circuit
events, fast protection against wire faults and arc faults,
controlled charging of capacitive loads, and protection against
inductive load switching and lightning. The configuration of the
elements described above provide an electrical system topology that
is tolerant of switch failure events including failure to open or
close, tolerant of unsynchronized switching and provides secondary
protection for each switch. Additionally, the topology can be
implemented as unidirectional or bidirectional.
[0042] To the extent not already described, the different features
and structures of the various embodiments can be used in
combination with each other as desired. That one feature cannot be
illustrated in all of the embodiments is not meant to be construed
that it cannot be, but is done for brevity of description. Thus,
the various features of the different embodiments can be mixed and
matched as desired to form new embodiments, whether or not the new
embodiments are expressly described. All combinations or
permutations of features described herein are covered by this
disclosure.
[0043] This written description uses examples to disclose the
embodiments, including the best mode, and also to enable any person
skilled in the art to practice the embodiments, including making
and using any devices or systems and performing any incorporated
methods. The patentable scope of the application is defined by the
claims, and can include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
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